Is this a correct way to do procedural bumps in Cycles?
While i am not an expert in the way blender nodes work, I think that it would be more precise to use the Fac (Factor) connector instead of color.

The color connector in the noise node creates a color output thats not black and white, thats then converted into height data in the bump node.

The Fac connector will generate non-color data that then is used to generate height information. 

There is a significant difference in how your bump map will look depending on which connector you use. The Fac connector should be more accurate for height data.



You can see the difference here on how it works.
The top squares use the Fac and Color connectors respectively directly as the diffuse input and below are those values plugged into the bump node to generate height.